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Ari Erenthal

A master can call any sub or any master. A sub can only ring (initiate a tone on all masters). A master must then initiate a call, which allows hands-free conversation between master and sub. Masters can also monitor subs. They sell subs with and without a privacy button.

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Brian Rhodes

Using that system, selective call means 'mesh' or station-to-station calling is supported. The LEF is one example of a small analog system that supports this, although there are others. 'Small' systems generally mean less than 12 - 16 units and typically are audio only.

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Undisclosed #2

Correct me if I'm wrong please - The LEF does not require additional equipment, but its wiring for a selective/all2all configuration, is a 20 wire (per station) $@# mesh...If you add this to the single talkpath, non-integration and non-expansion limitations - it is obvious that Axis strives to introduce a <$200 intercom station in the near future.

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Brian Rhodes

This is a good point, and while LEF series is not a 20 wire system in all configurations, the bottom line is you need to pull and install many wires, to a degree that a single bundle of UTP Cat 5/5e/6/6a is simple in contrast.

The exact wire config varies depending on mix of station types, but consider this example setup that requires 10 wires connecting stations together:

Even when these exact stations aren't used (other LEF series stations might be), the wiring requirements are heavy:

For an 11 station system, at least 15 wires are needed, even more if standard things like strike releases are installed.

The bottom line: while central exchangeless analog systems are available, the cost of additional wire runs and connections can be substantial.

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Luis Carmona

Great article, Brian. A subject that needed touching on for awhile. Surprises me there is still so many little integration with ACS and VMS (I know there's some, I'm saying more). But it seems like one of those things that should just be a logical extension. With the advent of SIP, there is really no excuse why more ACS and VMS systems should not be able to integrate with intercom devices.

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Alon Brown

I wonder when will the different substations, by different vendors/manufacturers, shown in the picture, be able to "converse" among themselves across the network, based on an open/standard integration platform...

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Rui Silva

Long distances are also an advantage of analog systems. Analog systems can handle distances longer than 400m easily, while IP systems are limited to 100m (without fiber or switches). Depending on the type of installation, this can make a big difference in cabling costs and infrastructures needed.

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Undisclosed #2

Yes, but you need dedicated cabling instead of unified (catX) cabling, and you will probably need a separate power supply for units 400 m away. I believe most of us prefer the notion of "intelligent infrastructure", which can be extended, expanded and monitored easily, while providing both centralized and distributed capabilities.

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Brad Anderson

Commend digital stations (2 wire) can go 1500m. If wire needs to be retained a pair is all that is needed without compromise of audio quality, 16kHz, full hands free open duplex, full supervision, scream alarm technology with units and modules for every environment.

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Undisclosed End User #3

This is a seriously under explored segment and thanks to IPVM for giving it some attention.

Been using an aiphone system for years, lots of options for localized mesh installs (JP series using twister pair to the door and Cat5 between masters) or remote reception functions (the later using IP converters to software at the headend 2500 miles away).

Biggest challenge now is finding a hybrid of both worlds as our business evolves, something local during core hours which can be forwarded to a central station after hours. Their AI series is getting close but has limited VMS partners and I'm generally reluctant to deploy IP intensive solutions due to management and cyber concerns, something to be said for the simplicity of analog when troubleshooting. Then there's the issue of audio quality with IP, not the best experience in the remote reception role.

Digital Accoustic's caught my attention at one time but has a limited catalog compared to AiPhone, and to fully realize the potential of a VMS as a PSIM through SIP requires the decision to commit. Heard good things about Security Centre, anyone have experience going all-in with Genetec?

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